Exhaust silencer



Dec. 31 1957 J. SPECK EXHAUST SILENCER Filed Aug. 8, 1956 United States Patent '0 EXHAUST SILENCER Josef Speck, St. Gallen, Switzerland Application August 8, 1956, Serial No. 602,746

Claims priority, application Switzerland August 13, 1955 Claims. (Cl. ISL-64) This invention relates to sound absorbing equipment for internal combustion engines and more particularly to mufllers or silencers which are attached to the exhaust pipe of such engines.

The subject of this invention is a muffler or silencer attached to the end of the exhaust pipe of an internal combustion engine, comprising duct means and a bucket wheel rotatably mounted in a chamber having inlet ports, connected to that duct means and an outlet port, communicating with an expansion chamber and outlet means from said expansion chamber to the atmosphere.

It is an object of the invention to interrupt the stream of the exhaust gas by means of a bucket wheel.

According to the invention the exhaust gases are divided into a long main stream and a short auxiliary stream, whereby the main stream is caused by a guide elbow having a bend of about 180 degrees to impinge on the blade wheel in the reverse direction to the general direction of exhausting, while the auxiliary stream impinges on the blade wheel in the general exhausting direction and the reuniting of the main and auxiliary streams take place in quickly rotating cells between the blades and provided in the wheel casing which has an outlet opening into an expansion chamber.

Actual tests with this noise silencer show that by making the exhaust gases in a long main stream and in a short stream flowing into the blade wheel casing in reverse direction to the main stream, it is possible to attain a reduction of at least 50% in noise.

A constructional example of the invention is illustrated in the accompanying drawings, wherein:

Figure l is a diagrammatic longitudinal section through the noise silencer, and

Figure 2 is a view partly in longitudinal section drawn to a larger scale.

Referring to the drawings, the exhaust silencer shown therein has an outer jacket formed of two easily releasable tubular parts 1, 2, stuck one in the other and having a narrowed front end with a connecting piece 3 and a narrowed rear end with a pipe 4 which can be changed for another pipe. The pipe 4 is provided with a screwthread with abutment collar 5 and with a nut 6 arranged on the screwthread. The rim of the rear opening of the tubular jacket part 2 is clamped between the abutment collar 5 and the nut 6. The pipe 4 has a part 4' which is provided with outlet openings 7, and the part 4' pro jects into an expansion chamber 8 of the tubular jacket part 2. The interengaging margins of the tubular jacket parts 1, 2 are connected together by a screw 9. An insert 10 composed of two assembled parts is pushed into the tubular jacket part 1. Both parts are provided with flanges 11, 12, and are screwed together at the flanges. The rear part of the insert 10 has a blade wheel casing 13 in which a blade wheel 15 is rotatably mounted by means of a shaft 14. The blade wheel casing 13 is provided with an inlet opening 16 facing in the direction of flow of the arrow at (Fig. 1) of the exhaust gases and with an inlet opening 17 facing in the reverse direction to the direction of flow a. The insert 10 has also a main passage 18 consisting of a tubular connection 18a which is connected to the flange 11 and extends in reverse direction to the general direction of flow of the exhaust gases, and of a passage 18]) which is connected to the blade wheel casing 13 and narrows in cross-section. The passage 18b forms in front of the inlet opening 17 a reversing elbow 19 the bend of which is about degrees. 20 is an auxiliary passage which branches from the tubular connection 18a and is formed by a tubular part 20a and a tubular part 20b connected by the flanges 11 and 12 to the part 20a. The insert 10 is held in position in the tubular jacket 1 by the flanges 11, 12, and by supports 21 arranged at the front end of the tubular connection 18a and is secured against longitudinal displacement by the screw 9 which engages a screwthreaded eye 22 of the insert 10. The blade wheel casing 13 has on that side which faces the pipes 4, 4, anoutlet opening 23 at which the exhaust gases expand on leaving the blade wheel casing.

The exhaust gases flow through the exhaust silencer in the direction of the arrow :1. They firstly enter into the main passage 18 and to a smaller extent into the auxiliary passage 20. The exhaust gases branching off into the auxiliary passage 20 impinge on the blade wheel in the direction of the arrow a, whereas the exhaust gases flowing through the main passage are first compressed and then guided in the reverse direction and thereupon impinge on the blade wheel in a direction which is opposite to the exhaust flow direction :1. Due to the high speed of rotation of the blade wheel (up to 7,000 revolutions per minute), the exhaust gases from the main stream in passing through the blade wheel casing are driven at the outlet opening 23 in to the separate cells formed between the blades, by which means the exhaust gases enclosed in these cells, before they reach the outlet opening 23, are mixed with the exhaust gases from the auxiliary passage, whereupon they escape into the expansion chamber. The exhaust gases flow around the pipe 4 and its part 4' in the expansion chamber and escape through the openings 7 from the said chamber into the open air.

The number of the outlet openings 7 of the pipes 4, 4' is in accordance with the number and volume of the cylinders of the motor provided with the exhaust silencer. For this purpose the pipe is arranged readily exchangeable for a similar pipe having however a larger or smaller number of outlet openings.

When the exhaust gases are flowing through the exhaust silencer, there is no congestion of the gases by a passage cross-section which is too small and therefore reduces the efiiciency of the motor. T o the contrary the gases have an unhindered passage. The increased noise reduction is attained mainly by alternate successive restrictions and enlargements of the cross-section of the flow and the division of the gas stream into two stream parts which are unequal in length and join together in the cells of the rotating blade wheel.

The hereinbefore described noise silencer has light individual parts: 2 parts 1, 2, of the tubular jacket, pipes 4, 4', both parts of the insert 10, and the blade wheel 15 which is insertable and removable through a lateral cover (not shown) of the blade wheel casing 13.

I claim:

1. A muffler, for use in connection with the exhaust pipe of an internal combustion engine, comprising in combination a jacket structure defining on its interior an elongated chamber and adapted to be connected with one end to said exhaust pipe, a casing disposed in said chamber and having a large inlet and a small inlet and having an outlet opening into said chamber, a bladed wheel freely rotatably journalled in said casing, duct means disposed in said chamber and operable to conduct gases, emanating Patented Dec.31', 1957" 3 from said exhaust pipe, to said wheel and comprising a main duct connected to said large inlet for intercommunication between the interior of said main duct and the interior of said casing and including a one-half turn bend whereby the exhaust gases will in said main duct be first conducted substantially in the direction of exhaust and thereafter prior to entry into said chamber will be conducted in a direction opposite thereto, a branch duct having a cross section smaller than that of said main duct, and being connected to said main duct upstream of the bend thereof and connected to said small inlet of said casing and being operable to tap a portion of the stream of exhaust gases ofi said main duct and to conduct that stream portion in substantially the exhaust direction into said casing, whereby the blades of the wheel in said casing will be impinged by a large stream of exhaust gases in a direction opposite to the exhaust direction and by a small stream substantially in the exhaust direction, said streams being expelled from said casing through said o'ut let into said chamber, and gas exit means operable for 20 passing the gases from said chamber to the exterior near the opposite end of said structure.

2. In a mulfler as claimed in claim 1, said gas exit means comprising a pipe interchangeably mounted in said jacket structure and including a perforated section extending into said chamber.

3. A muffler as claimed in claim 1, said jacket structure being composed of two separable parts, said casing and duct means being removably positioned in the chamber within said jacket structure.

4. In a muffler as claimed in claim 1, said main duct including a constriction adjacent said large inlet.

5. In a muffier as claimed in claim 1, said main duct being in said chamber spaced from the internal surface of said jacket.

References Cited in the file of this patent UNITED STATES PATENTS 1,045,614 Sames Nov. 26, 1912 2,661,073 Deremer Dec. 1, 1953 FOREIGN PATENTS 919,931 France Dec. 16, 1946 177,972 Austria Mar. 25, 1954 

